1. Field of the Invention
This invention relates to a housing assembly for an electrical switching apparatus and, more specifically, to a housing assembly having no protrusions extending outwardly from the lateral sides.
2. Background Information
An electrical switching apparatus is typically disposed in a housing assembly. The housing assembly is, typically, a rectangular box having a back sidewall, a top sidewall, a bottom sidewall, a right sidewall, a left sidewall, and a front sidewall. Selected sidewalls, typically the back sidewall or the top and bottom sidewalls, have openings therethrough which are structured to accommodate the line and load conductors for the electrical switching apparatus. The front sidewall may be movable, or removable, so as to allow access to the enclosed space defined by the housing assembly. An electrical switching apparatus may be disposed in the enclosed space defined by the housing assembly and coupled to the line and load conductors. Often a plurality of electrical switching apparatuses will be disposed within a single housing assembly. Other times individual electrical switching apparatuses will be disposed within a sub-housing assembly, also called a cassette, within a larger housing assembly.
Within a cassette there are a number of components that are coupled to the cassette walls. For example, certain types of electrical switching apparatus have a considerable weight and are typically moved into and out of the cassette on a pair of tracks or rails. The fasteners for the rails typically extend through the rail assembly and through a lateral wall. The fastener, which is typically a bolt, has an associated capture device, i.e. a nut. In this configuration, the bolt head or the nut is disposed on the outer side of the cassette. Other fasteners also extend through the lateral sides of the cassette. For example, the cassette is typically constructed from generally flat sheets of metal. The edges of selected sidewalls, the lateral edges of the bottom sidewall for example, may be bent to about a right angle thereby creating a mounting tab. The mounting tab and the associated lateral sidewall will have a fastener opening therethrough. When a fastener, again a bolt/nut is typical, is inserted into the opening, either the bolt head or the nut will be disposed on the outer side of the lateral sidewall.
When the cassette is used independently, having fasteners disposed on the outer side of the lateral sidewall is acceptable; however, when multiple cassettes are disposed in a larger housing assembly side-by-side, the fasteners disposed on the outer side of the lateral sidewall are difficult to access and require extra space. That is, two cassettes cannot be placed immediately adjacent to each other because of the exposed fasteners. Also, when such cassettes are placed as close together as possible, it is very difficult to access the fasteners disposed between the cassettes. Thus, a simple repair procedure may require the removal of both enclosed electrical switching apparatuses so that the cassettes may be broken down for repair. Where cassettes are disposed vertically, the same problems may be seen with fasteners extending through the top and bottom sidewalls. Further, while fasteners disposed through other sidewalls, e.g. the back sidewall, where the bus assembly is typically located, do not generally cause interference problems, these fasteners may still be difficult to reach.
One method of addressing these problems is to have fasteners extend through adjacent lateral sidewalls. That is, a single fastener may be passed through a rail assembly in a first cassette, the sidewall of the first cassette, the sidewall of an adjacent cassette, and the rail assembly of the adjacent cassette. This configuration is also not optimal, however, as both cassettes must have the enclosed electrical switching apparatus removed to repair, for example, a single rail assembly.
There is, therefore, a need for a cassette for an electrical switching apparatus that may be disposed immediately adjacent to another laterally disposed cassette.
There is a further need for a cassette for an electrical switching apparatus wherein all attachment hardware may be accessed from inside the enclosed space.